ORACLE RAC 記憶體SGA，PGA配置超過300G的問題

As every customer environment is unique, the success of any Oracle Database implementation, including implementations of Oracle RAC, is predicated on a successful test environment. Oracle Support has identified 100 GB as a baseline for large SGA's that would benefit from the recommendations provided in this note. However, this is just a baseline, and it is possible for similar(but smaller) SGA's to benefit from these recommendations. It is thus imperative that any recommendations from this note are thoroughly tested and validated using a testing environment that is a replica of the target production environment before being implemented in the production environment to ensure that there is no negative impact associated with the recommendations that are made

a.      Set _lm_sync_timeout to 1200 
           Setting this will prevent some timeouts during reconfiguration and DRM. It's a static parameter and rolling restart is supported.


b.      Set _ksmg_granule_size to 134217728
           Setting this will cut down the time needed to locate the resource for a data block. It's a static parameter and rolling restart is supported.

c.      Set shared_pool_size to 15% or larger of the total SGA size.
        For example, if SGA size is 1 TB, the shared pool size should be at least 150 GB. It's a dynamic parameter.

d.      Set _gc_policy_minimum to 15000
        There is no need to set _gc_policy_minimum if DRM is disabled by setting _gc_policy_time = 0. _gc_policy_minimum is a dynamic parameter, _gc_policy_time is a static parameter and rolling restart is not supported. To disable DRM, instead of _gc_policy_time, _lm_drm_disable should be used as it's dynamic.

e.      Set _lm_tickets to 5000
        Default is 1000.   Allocating more tickets (used for sending messages) avoids issues where we ran out of tickets during the reconfiguration. It's a static parameter and rolling restart is supported. When increasing the parameter, rolling restart is fine but a cold restart can be necessary when decreasing.

f.      Set gcs_server_processes to the twice the default number of lms processes that are allocated.
        The default number of lms processes depends on the number of CPUs/cores that the server has, 
        so please refer to the gcs_server_processes init.ora parameter section in the Oracle Database Reference Guide 
        for the default number of lms processes for your server.  Please make sure that the total number of lms processes 
        of all databases on the server is less than the total number of CPUs/cores on the server.  Please refer to the Document 558185.1 
        It's a static parameter and rolling restart is supported.